增函數(shù)+增函數(shù)=增函數(shù) 證明：設(shè)f(x)、g(x)單增,則f'(x)>0,g'(x)>0,(f(x)+g(x))'=f'(x)+g'(x)>0,證畢.增函數(shù)+減函數(shù)=不明 證明：設(shè)f(x)單增,g(x)單減,則f'(x)>0,g'(x)0,g'(x)>0,(f(x)/g(x))'=(f'(x)g(x)-f(x)g'(x))/(g'(x))^2大小不明.減函數(shù)/減函數(shù)=無法判斷 證明：類似上.增函數(shù)包含增函數(shù)=增函數(shù) 證明：設(shè)f(x)、g(x)單增,則f'(x)>0,g'(x)>0,(f(g(x)))'=f'(g(x))g'(x)>0,證畢.減函數(shù)包含減函數(shù)=增函數(shù) 證明：類似上 增函數(shù)包含減函數(shù)=減函數(shù) 證明：類似上.減函數(shù)包含增函數(shù)=減函數(shù) 證明：類似上.